. The chemistry and mode of action of plant growth substances; proceedings of a symposium held at Wye College, University of London, July 1955. Plant regulators; Auxin; Growth (Plants). Investigation of natural auxins and growth inhibitors as above and assayed with oat coleoptile segments. The results shown in Figure 2 were obtained. It is clear from Figure 2 that for bean seed tissue methanol seems to be a better solvent than ethanol, since the peaks of growth, especially the one in the indole-3-acetonitrile (IAN) region, are higher. It seems also that ethyl acetate extracts a still higher am
. The chemistry and mode of action of plant growth substances; proceedings of a symposium held at Wye College, University of London, July 1955. Plant regulators; Auxin; Growth (Plants). Investigation of natural auxins and growth inhibitors as above and assayed with oat coleoptile segments. The results shown in Figure 2 were obtained. It is clear from Figure 2 that for bean seed tissue methanol seems to be a better solvent than ethanol, since the peaks of growth, especially the one in the indole-3-acetonitrile (IAN) region, are higher. It seems also that ethyl acetate extracts a still higher amount of auxins, although the peak in the IAN region is less marked; in addition, ethyl acetate appears to extract a substance having a /?^ higher than lAA but lower than IAN. To find out whether ethyl acetate was a better solvent than methanol, the following experiment was performed. Lyophilized immature bean seeds were first extracted for one and a half hours with absolute methanol at 0°C, then with anhydrous ethyl acetate for another one and a half hours, also at 0° Figure 2. Histograms made under conditions similar to those of Figure 1. except that the three extracts are of 15 mg {dry weight) each of lyophilized bean seeds {var. Dwarf Shell Red Kidney), dissected out of the immature pods about one week after /lowering. The extractions were made at 0 C during 5 hours with absolute methanol, absolute ethanol. and ethyl acetate respectively. The material extracted with ethyl acetate ivas washed with absolute ethanol and the two extracts were combined. The two extracts were chromatographed separately in our new /j-obutanol (80)+methanol (5) +H2O (15) (v/v) solvent which has been substituted for the previous one for reasons which will be discussed below. The results obtained when the chromatograms were assayed with oat coleoptile segments (see Figure 3) show clearly that after the methanol extraction, which yields large quantities of auxins, ethyl acetate extracts only very
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